From be84cecfeb560a013857fa9a5326eca7b785cb5d Mon Sep 17 00:00:00 2001
From: XANTRONIX Development <dev@xantronix.com>
Date: Mon, 6 Jun 2016 20:28:19 -0500
Subject: [PATCH] I hate overflows as much as the next person

---
 avr/Makefile                |  2 +-
 avr/printer.c               | 18 ++++++++++++++++++
 avr/recv.c                  |  7 ++++---
 avr/send.c                  |  7 +++++++
 include/tabby/avr/printer.h |  2 ++
 5 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/avr/Makefile b/avr/Makefile
index 46b910a..f85ac71 100644
--- a/avr/Makefile
+++ b/avr/Makefile
@@ -29,7 +29,7 @@ OBJS		= send.o recv.o printer.o link.o uart.o
 RECV_NAME	= recv
 RECV_BIN	= $(RECV_NAME).bin
 RECV_ELF	= $(RECV_NAME).elf
-RECV_OBJS	= recv.o link.o uart.o
+RECV_OBJS	= recv.o printer.o link.o uart.o
 
 SEND_NAME	= send
 SEND_BIN	= $(SEND_NAME).bin
diff --git a/avr/printer.c b/avr/printer.c
index 3fed9c1..17000d6 100644
--- a/avr/printer.c
+++ b/avr/printer.c
@@ -3,6 +3,24 @@
 #include <tabby/avr/link.h>
 #include <tabby/avr/printer.h>
 
+int tabby_avr_printer_packet_toolarge(uint8_t type, uint16_t size) {
+    switch (type) {
+        case TABBY_PRINTER_PACKET_JOB: {
+            if (size > sizeof(tabby_printer_job)) {
+                return 1;
+            }
+        }
+
+        case TABBY_PRINTER_PACKET_DATA: {
+            if (size > TABBY_PRINTER_PACKET_MAX_SIZE) {
+                return 1;
+            }
+        }
+    }
+
+    return 0;
+}
+
 static uint16_t checksum(tabby_printer_packet *header, uint8_t *body) {
     uint16_t sum = 0;
 
diff --git a/avr/recv.c b/avr/recv.c
index 27392b7..6d5046a 100644
--- a/avr/recv.c
+++ b/avr/recv.c
@@ -2,7 +2,7 @@
 #include <avr/interrupt.h>
 #include <avr/sleep.h>
 
-#include <tabby/printer.h>
+#include <tabby/avr/printer.h>
 #include <tabby/avr/uart.h>
 #include <tabby/avr/link.h>
 #include <tabby/avr.h>
@@ -66,12 +66,13 @@ ISR(SPI_STC_vect) {
 
         case 5: {
             header.size |= in << 8;
-            i++;
 
-            if (header.size > TABBY_PRINTER_PACKET_MAX_SIZE) {
+            if (tabby_avr_printer_packet_toolarge(header.type, header.size)) {
                 i = 0;
             }
 
+            i++;
+
             break;
         }
 
diff --git a/avr/send.c b/avr/send.c
index 59bcb16..91476ab 100644
--- a/avr/send.c
+++ b/avr/send.c
@@ -115,6 +115,13 @@ int main() {
                 header.size |= c << 8;
                 i++;
 
+                if (tabby_avr_printer_packet_toolarge(header.type,
+                                                      header.size)) {
+                               i = 0;
+                               b = 0;
+                    sheet_offset = 0;
+                }
+
                 break;
             }
 
diff --git a/include/tabby/avr/printer.h b/include/tabby/avr/printer.h
index d12074e..390423e 100644
--- a/include/tabby/avr/printer.h
+++ b/include/tabby/avr/printer.h
@@ -5,6 +5,8 @@
 
 #include <tabby/printer.h>
 
+int tabby_avr_printer_packet_toolarge(uint8_t type, uint16_t size);
+
 void tabby_avr_printer_send_packet(uint8_t type,
                                    uint8_t *body,
                                    uint16_t size,